The need for low cost manufacturing and high circuit density in the electronics industry is resulting in greater use of multilayer or laminated structures. One such application in the disk drive industry is to combine the disk drive suspension and the conductors interconnecting the head and the disk drive electronics. Briefly, disk drives are information storage devices which utilize at least one rotatable disk with concentric data tracks containing the information, a head (or transducer) for reading information from or writing information to the various tracks, and a head positioning actuator connected to the head for moving it to the desired track and maintaining it over the track centerline during read or write operations. The transducer is attached to an air bearing slider which is supported adjacent to the surface of the disk by a cushion of air generated by the rotating disk. The slider is connected to the head positioning actuator by means of a suspension.
Electrical conductors communicate information between the disk drive electronics and the head. The communicated information is data read from the disk or written to the disk by the head.
Conventionally, the electrical conductors have been individual wires, which may be strung along the suspension and connected individually to other wires which lead to the drive electronics.
With the advent of multilayered or laminated structures for disk drive suspensions, the electrical conductors are combined into the suspension structure as a single unit. Briefly, such a structure comprises a base layer of stainless steel, and a top layer of copper or copper alloy, separated by a dielectric layer like polyimide. Each of the layers are patterned so that the structure behaves as an integrated lead suspension. Such integrated lead susepnsions can be produced either by a subtractive or additive process. The electrical leads in such suspensions terminate in a set of electrical pads located linearly adjacent each other at the ends of associated parallel conductors.
Multiconductor flex cables are widely used in the electronics industry, and are used in disk drives for connecting the conductors from the heads, at the back end of the actuator, to the drive electronics. The actuator and the suspension move the head from track to track, while the drive electronics are stationary. Thus, the multiconductor flex cable provides the flexible connection accommodating the head movement.
Typically, such cables comprise a polyimide base layer and flex thin leads disposed thereon, with a top cover laminated to the base layer. The leads are most often formed by subtractive processes wherein a copper lamination on the base layer is etched to form a plurality of parallel conductors for the full length of the base layer. Other processes (i.e., additive) are sometimes used to provide the parallel conductors.
Individual wires, when used to connect the head transducer to the drive electronics flex cable, although more labor intensive, still allow each wire to be positioned precisely to make an electrical connection, as the individual wires are flexible. The advent of integrated lead suspensions, together with multiconductor flex cables, requires precise alignment of all of the pads of integrated lead suspension conductors to the corresponding pads of the flex cable conductors, as these conductors, unlike wires, can not be manipulated. One approach at making an electrical connection between a multiconductor flex cable and electrical pads at the termination ends of the conductors of an integrated lead suspension is to place the cable and electrical pads of the suspension at right angles to one another with solder bumps on the electrical pads, and heating the solder bumps at the connection. However, this requires precise alignment of the pads on both the suspension and the multiconductor flex cable. Without complete alignment, making electrical connections at all of the pads is very difficult, and is prone to failure.